its important to have water level in sump steady for all skimmers. maybe you can add a baffle to sump. try to have output of skimmer halfway in and halfway out and parallel to water level in sump. this will help make it more quiet. the more you submerge the output the more back pressure on pump. this is like having a valve on the pump and closing it a little, which is ok. i have a gate valve on my pump so i can have fine control. you dont need a gate valve, but i tried it and like it.